The multi-layer coil separator is a new countercurrent chromatographic device for the efficient and rapid separation of chemical mixtures by means of partitioning between two immiscible liquids. The device has been commercially available for three years and is being increasingly applied to the isolation and purification of medicinally useful products of natural and synthetic origin. Its mild environment and the lack of adsorptive components make it especially useful for separation of biologically active substances. Although a wide range of solvents can be used, more viscous solvents behave erratically. An immediate goal of this research is to construct and test a heated countercurrent chromatograph, which will lower viscosity, promoting more uniform hydrodynamic behavior of the solvent, and which will double the capacity of the device by increasing solubility. A second goal is to improve the chromatographic efficiency of the coiled columns employed in the unit. To do this, the effect of several variations in colums construction on efficiency and on the resolution of test substances will be measured with the aim of optimizing the geometry and physical structure of the columns. In the course of the work, valuable data on the properties of solvent systems will be obtained and published to benefit scientists who use this technology. Countercurrent chromatography facilitates separations of substances which were previously difficult to purify. It provides an improved method for purification of polar, water-soluble substances and labile materials when used alone or as an adjunct to HPLC.